Modern weapon systems utilize today the infrared (IR) part of the electromagnetic spectrum in addition to the visible spectrum. Especially the weapon systems which have been developed to defeat armoured fighting vehicles, comprise sighting devices operating in the infrared spectrum, which means that hostile objects can be observed and aimed at as well in daylight as in the dark.
Further, modern weapon systems utilize the millimeter band of the electromagnetic spectrum, for example in the range of 35-94 GHz, for observation, homing and destroying hostile objects.